The gay marriage battle has taken a significant step towards the Supreme Court today. No, the verdict hasn’t yet been announced in California’s Proposition 8 case. Rather, a federal district court in Massachusetts, in a pair of cases, has declared the Defense of Marriage Act, or DOMA, unconstitutional as applied to states and individuals.

A federal judge in Boston — Judge Joseph L. Tauro (D. Mass.), appointed to the bench by President Nixon back in 1972 — just issued a ruling striking down Section 3 of the Defense of Marriage Act (DOMA). As you may recall, DOMA is the 1996 law that effectively bans recognition of same-sex marriages for purposes of federal law.

As this case seems destined for One First Street, somewhere Elena Kagan is thankful she didn’t commit to Sen. Chuck Grassley’s questioning her over the precedential value of Baker v. Nelson, the 1971 Minnesota Supreme Court case that held that a state law restricting marriage to the union of a man and a woman did not violate the Constitution–a holding that the United States Supreme Court dismissed on mandatory appeal in 1972 “for want of a substantial federal question.”

And somewhere in Iowa, Grassley is CTRL-F’ing the two opinions for any mention of Baker v. Nelson, only to find no mention of it by Judge Tauro.

In fact, by prefacing his questions to Kagan with the assertion, “Marriage is a state issue,” Grassley framed Baker v. Nelson in a way favorable to the prevailing plaintiffs in today’s rulings. After all, Judge Tauro’s opinions struck to the heart of a federal law that cut against a state’s decision to recognize same-sex marriages.

But Grassley had not the Massachusetts cases in mind, but rather the Prop 8 case, Schwarzenegger v. Perry, in which a state constitutional amendment limiting marriage to a man and a woman violates the federal constitution. On this point, Perry is the opposite of the Massachusetts cases: whereas Mass v. HHS asserted a state’s traditional supremacy in marriage matters over federal statutory meddling, the plaintiffs in Perry seek federal supremacy over a popularly-passed state constitutional provision.

Where the two come together, however, is in Gill. Just as the Perry plaintiffs seek cover of the federal constitution’s guarantee of equal protection, so did the Gill plaintiffs prevail on that very claim. The difference, of course, is that Gill employs the federal constitution to strike down a federal law; the Perry plaintiffs seek to use the same provision to strike down a state law.

But that may be a distinction without a difference when it comes to an equal protection claim rooted in sexual orientation discrimination–a concept that had no popular support or force of law when the Court passed on Baker v. Nelson in 1972. But Romer v. Evans and Lawrence v. Texas set the Court on the path towards looking at state marriage laws that make classifications between sexual orientations with similar suspicion to those that did so on the basis of race. And the Court surely meddled in the state’s traditional power to regulate marriage when it did find enough of a substantial federal question in the anti-miscegenation statutes in struck down in 1967’s Loving v. Virginia.

The question now, however, is whether Justice Kennedy, the author of both Romer and Lawrence and the putative fifth vote in a gay marriage case, is willing to extend his sexual orientation discrimination jurisprudence the same way he has expanded his death penalty jurisprudence. In other words, is recognizing a federal constitutional right for same-sex marriage more akin to sheltering juveniles from life without parole for non-homicide crimes, or is it more like deeming the death penalty at all times unconstitutional under the Eighth Amendment? If the former, the Perry plaintiffs can take heart. If the latter, Perry may fail to gain Kennedy’s approval, and Gill and Mass v. HHS will become the preferred precedents in the fight for marriage equality.

Either way, though, Grassley’s implication that marriage, unlike criminal law, remains free from federal constitutional scrutiny rests on shaky historical foundations. But then, if we take that notion seriously, what does that say about Tauro’s opinions today?

Over at Concurring Opinions, Brandon Bartels has posted an interview with me about F1@1F for the legal blog’s “Bright Ideas” series. Here’s a sample:

What unique insights have your experiences over the past term given you about the Supreme Court and the justices?

Chief Justice Roberts is a superb political strategist. He’s steering a right-of-center Court through a left-of-center government and knows which storms his ship can handle and which it cannot. I wrote prospectively about this back in December, Jeff Rosen of The New Republic wrote about it in February, and Adam Liptak of the New York Times wrote about it just the other day.

What we’ve seen this year is the birth of John Roberts’ Court. It will always, to a degree, remain the Anthony Kennedy Court as well, until he leaves the bench or one of the conservatives is replaced by a liberal. But Roberts took control this year in the Court’s decisionmaking that we haven’t yet seen. The next interesting thing to look out for is what issues beyond Miranda, guns, arbitration, and campaign finance the Chief believes are ripe for conservative gains as the Congress and the Presidency remain in Democratic hands.